1948 Oldsmobile with Drivability Issues

[57j2olds]

Hello Folks,

 

So this project has been driving me nuts. 

 

1948 Olds with 1949 6 cyl motor. Hydramatic

 

I bought this all original car without a ton of history behind it. The guy I got it from was going to pull the straight 6 and make it a hot rod. I saved it......I hope.

 

The motor idles like new. In neutral, manually opening carb while running, seems to fall on face. Almost like fuel starvation. 

 

Upon acceleration in drive the car shakes like mad. It's difficult to get it up to 35mph let alone 10 mph. After I finally get it out of first I have to feather the gas pedal to get it up to speed.

 

So far I have replaced:

 

• Fuel pump
• Carb
• Installed Pertronix ignition (removed points). Timing is set. 
• Flushed transmission (and converter)
• Water pump
• Radiator
• Plugs
• Gas Tank

 

I recently noticed 2 things that may contribute (please comment) to these issues:

 

• An aftermarket (Fram clear type) fuel filter that's under the car looks like not much fuel flow. I plan to remove it this weekend.
• Looks like the owner out a ton of black "goop" in and around the motor and trans mounts. I think these are shot. Could this be vibe issue? Bad torque converter? 
• Wondering if the re-build carb (Carter WA-1) I bought online is bad?
• Thinking about getting this one - https://www.amazon.com/gp/product/B075VQHC9C/ref=ox_sc_saved_title_1?smid=A3DH28W4SZLXRV&psc=1

 

Any input would be greatly appreciated. 

 

 

 

[dalef62]

Did you replace or check the fuel line from the tank to the pump.  I had a 41 Olds that the line was rusted out as it went over the rear axle and instead of the pump sucking fuel, it sucked air in from the holes.  And because the holes were on the top of the line and over the rear axle it didn't leak any fuel.  It would idle fine and stumble on acceleration.

Good luck in your search,

Dale

[57j2olds]

Hi Dale,

 

I'll check this out as well. Thanks much.

 

Lee

[m-mman]

3 hours ago, dalef62 said:

I had a 41 Olds that the line was rusted out as it went over the rear axle and instead of the pump sucking fuel, it sucked air in from the holes.  And because the holes were on the top of the line and over the rear axle it didn't leak any fuel.

This situation can be tested through vacuum.

Plug one end of the metal line and use a hand held vacuum pump at the other. It should quickly draw a vacuum but most importantly it should HOLD the vacuum. If the metal line doesn't hold a vacuum, you have a leak somewhere. 

[M1842]

The distributor vacuum advance can also cause this shake and lack of power if it no longer holds a vacuum.  Disconnect the line that goes from carb to the advance unit on the distributor and hook up a vacuum pump, if the vacuum advance won't hold a vacuum, it's shot and needs to be replaced.   Relatively cheap item.

[carbking]

Test, stop throwing new parts (and money) at the problem until you determine the problem.

 

(1) a compression test is the first test

 

IF THE COMPRESSION IS GOOD

 

(2) Ignition test - when you downgraded to the electronics, did you upgrade to an alternator? If not, I have no more specific suggestions.

 

If you did upgrade to the alternator, and the firing voltages AT THE PLUGS are what they should be

 

(3) fuel delivery test. Your shop manual should give you instructions on how much fuel the pump should pump into a container in a specified time.

 

If all of the above tests are normal, start looking for vacuum leaks, or hook up a vacuum gauge

 

If vacuum is good, then time to look at the carburetor. First make sure it is the correct one, if you bought it off the 'net.

 

Jon

[57j2olds]

2 minutes ago, carbking said:

Test, stop throwing new parts (and money) at the problem until you determine the problem.

 

(1) a compression test is the first test

 

IF THE COMPRESSION IS GOOD

 

(2) Ignition test - when you downgraded to the electronics, did you upgrade to an alternator? If not, I have no more specific suggestions.

 

If you did upgrade to the alternator, and the firing voltages AT THE PLUGS are what they should be

 

(3) fuel delivery test. Your shop manual should give you instructions on how much fuel the pump should pump into a container in a specified time.

 

If all of the above tests are normal, start looking for vacuum leaks, or hook up a vacuum gauge

 

If vacuum is good, then time to look at the carburetor. First make sure it is the correct one, if you bought it off the 'net.

 

Jon

Jon-

 

Downgrading the electronics meaning going HEI vs. stock points?

 

 

 

[Rivguy]

Is there a resistor lowering voltage to the distributor.? Most point systems either used a separate ceramic type resistor or a resistor wire. Some transistor ignitions need a full 12 volts to work. Check vacuum advance and advance weights in distributor. Good luck.

[carbking]

28 minutes ago, 57j2olds said:

Jon-

 

Downgrading the electronics meaning going HEI vs. stock points?

 

 

 

The comment was "downgrading TO the electronics" (implied - from points), not "downgrading the electronics".

 

In 61 years of driving, I have yet to walk with a set of points. Had to repair a broken contactor arm once, but never walked. With electronics, have walked TWICE, and would of walked more often if I didn't start carrying spare modules and the tools to change them on newer vehicles. Here in Missouri, where the relative humidity often EXCEEDS the ambient in the summer, every vehicle that I have ever owned averaged about 40k miles on electronic ignitions. One vehicle I still have is averaging less than 15k (factory electronics), and another vehicle that has been sold went through 13 units in 440k miles. I used to carry TWO new modules with me for this shop truck!

 

Of course, now we have cell phones to call the tow truck!  

 

And what you use is obviously your decision, but electronics DEMAND a stable voltage, which a generator is incapable of delivering. Was just trying to show a framework for testing procedure.

 

Over the last couple of decades, have solved hundreds of "carburetor problems" by suggesting to prospective carburetor customers an upgrade from the electronics conversion back to his/her original points.

 

Obviously, some of them work, or the company would go out of business, but really think they owe me for "customer service"  

 

And for what its worth, the Carter WA-1 was one of the most reliable single barrel carbs every built!

 

Jon

 

[Bloo]

I am on the fence about this. I like electronic ignition but it is important to keep in mind that it's chief advantage is it's ability to remain stable over time, not "run better" despite what 50+ years of advertising copy says.

 

There are some technical reasons I don't expect electronic ignition to work out well on a 6 volt car. I won't rehash all that again here, but I will say that anyone who really wants to do it should get the car running right first. Then try the electronic ignition.

 

I agree with others. It is time to get back to basics, starting with a compression test.

 

Edited July 12, 2022 by Bloo (see edit history)

[rocketraider]

Check your firing order and snoop around for a vacuum leak on carb and intake. Plug wires as well since you didn't mention those.

 

Faulty rubber mounts can contribute to vibration as can a faulty u-joint.

 

HydraMatic does not have a torque converter. It uses a fluid coupling but I've never seen one fail to point of vibrating like you've described.

[Ron of Chicago]

Plugged or partially plugged exhaust ?

[57j2olds]

I want to thank you all for the great advise.

 

I have the stock 6 volt system with no resistor. I only went to Electronic because of the exact same condition I was experiencing with points and was hoping it would fix it. 

I just check compression - 70 psi on every cylinder. 

 

I will checked what you all have suggested in the next few days. 

 

Thanks,

Lee

 

Edited July 13, 2022 by 57j2olds (see edit history)

[Bloo]

Someone mentioned the vacuum advance. Definitely check that. Also, though I can't say for sure without seeing it, the vacuum advance probably moves a plate inside the distributor while the distributor body is bolted stationary to the engine. If that is the case, there is a ground wire from the moving plate to the distributor case. It is made of some special wire meant to bend all the time when the vacuum advance moves without breaking. It is probably mixed strands of copper and spring steel. Make sure it is in there and not broken. A bad one causes the symptoms you describe, usually accompanied by popping in the exhaust.

 

While you are in there, it would be a good idea to make sure the centrifugal advance mechanism is free. A drop of oil down the center of the shaft (under the rotor) can't hurt.

 

Check your spark plug wires and coil wire with an ohmmeter. It can be hard to get a good connection on the spark plug end. If that is the case, use a non-resistor spark plug as an adapter. Touch the center terminal. End to end they should be a few ohms if copper, and maybe 2000-4000 ohms (2k-4k) if resistor type. The exact number doesn't matter much. On resistor wires the resistance is distributed evenly along the wire, so longer ones should be higher in resistance. That does matter. If you find an outlier, it is probably bad.

 

Look inside your distributor cap with a bright light for cracks. There is a carbon button in the center that must touch the rotor. Make sure it does. In a 1948 car, the button is probably spring loaded. Another possibility is that the carbon button is crimped in, and in that case a piece of bendy spring steel on the rotor reaches up to touch it. Either way, make sure the carbon is going to touch in the center.

 

If you found a problem with a bad (high resistance) coil wire or spark plug wire, or a problem with the carbon button, replace the rotor with a new one after you fix the problem.

 

Inspect your ignition coil's tower under a bright light for a crack leading from the tower down to one of the small terminals.

 

If/when using points (definitely a good idea until you get it sorted out), always try a new condenser.

 

Edited July 13, 2022 by Bloo (see edit history)

[57j2olds]

Is this telling me my compression should be at 160???

1000 RPM???

 

 

 

Edited July 13, 2022 by 57j2olds (see edit history)

[Bloo]

I guess it's telling you that. I would react with extreme skepticism. No way are you going to see 160 pounds on a 6.5:1 flathead six.

 

70 across the board might be a little low I guess, but it is about what I would have expected. since they are even, I think it is fine. Back to looking at the ignition (and maybe the carburetor).

 

Edited July 13, 2022 by Bloo (see edit history)

[57j2olds]

Here is my distributor.

 

I will check vacuum advance today.

 

 

 

[Aaron65]

Lee, when you did your compression test, did you prop the throttle wide open?  Were all the spark plugs out?  Is the battery in good shape (the faster it spins, the higher your number will be)?  It's good that they're even, but your testing technique could affect the actual number.

[roysboystoys]

If you do all of the steps mentioned above and still have a problem remove the carb and inspect the intake .

It may have burned through and allowing exhaust gas in.

I'm guessing you have an ignition problem, cap , rotor , wires, maybe even wrong firing order.

Edited July 13, 2022 by roysboystoys (see edit history)

[Bloo]

1 minute ago, roysboystoys said:

It may haveburned through and allowing exhaust gas in.

I was wondering about that. Pontiacs are notorious. Does Oldsmobile have that issue? If so, that is the next thing to check.

[Bloo]

Be sure that brown ground wire isn't broken. I also might arrange it so it is less kinked. It moves constantly.

[Ben Bruce aka First Born]

17 hours ago, 57j2olds said:

Jon-

 

Downgrading the electronics meaning going HEI vs. stock points?

 

 

 

 Yeah!   Some folks don't like electronic ign.  For what it's worth, I do.  Although with 6V the system is touchy. Voltage MUST be at 6 or more, I believe. Hook a charger to the battery and get it to 7V or so.  

 

  Your problem sounds like a fuel problem. The falling on it's face anyhow.  When the throttle is opened the engine sucks a LOT of air.  If there is not enough gas, it stumbles and falls.  Try spraying a little gas into the carb [ air cleaner off ] when opening the throttle. May be surprised. May not.  If was me, I would use a "boat" gas tank for trouble shooting.

 

  Ben

[57j2olds]

1 hour ago, Bloo said:

Be sure that brown ground wire isn't broken. I also might arrange it so it is less kinked. It moves constantly.

It looks like that ground wire that is pinched under the cap has lost insulation.........

[57j2olds]

1 hour ago, Aaron65 said:

Lee, when you did your compression test, did you prop the throttle wide open?  Were all the spark plugs out?  Is the battery in good shape (the faster it spins, the higher your number will be)?  It's good that they're even, but your testing technique could affect the actual number.

It's been years since I did a comp test....

 

No - I left the other plugs in when I did the test. 

 

No - I did not touch the throttle. Just cranked her over. Spun well on new battery. 

[Aaron65]

31 minutes ago, 57j2olds said:

It's been years since I did a comp test....

 

No - I left the other plugs in when I did the test. 

 

No - I did not touch the throttle. Just cranked her over. Spun well on new battery. 

If you're inclined, try it the way I mentioned.  Your numbers should improve significantly.  

You've gotten a lot of good advice here.  If it were my car, I'd do the following:

1. Check the mechanical advance (just twist the rotor by hand to see if it's free and if it returns freely).

2. Reinstall points and condenser and make sure the points gap is correct.

3. Check the timing.

4. Run the engine off a spare can of gas to see if the problem continues.

5.  Rig in a fuel pressure gauge to see if you have adequate fuel pressure to the carb.

 

If the problem persists, then you can get into the less likely (but still very possible) procedures.

Edited July 13, 2022 by Aaron65 (see edit history)

[Bloo]

36 minutes ago, 57j2olds said:

It looks like that ground wire that is pinched under the cap has lost insulation.........

The insulation won't matter on that one. A lot of them don't have insulation. What is important is for that moving plate to have a solid ground back to the case.

 

The wire the insulation matters on is the one to the points (when you were still using them). It is another special bendable wire.

[JACK M]

I got lost when the all original statement followed the 48 with a 49 motor.

My first thought after seeing the replaced parts list was that it did not show a fuel filter, but symptoms seem to indicate fuel starvation.

On a 70 plus year old car my tune ups always include plug wires.

 

And I have never installed a Pertronics in anything.

[57j2olds]

5 minutes ago, JACK M said:

I got lost when the all original statement followed the 48 with a 49 motor.

My first thought after seeing the replaced parts list was that it did not show a fuel filter, but symptoms seem to indicate fuel starvation.

On a 70 plus year old car my tune ups always include plug wires.

 

And I have never installed a Pertronics in anything.

Yes. I did some digging on the motor numbers and found that at one point in time the original 48 motor was swapped out for a 49. Probably blew it up back in the 50's.

 

It has an aftermarket in-line fuel filter that I need to eliminate. That's also on my list tonight. 

 

The wires look like they were replaced a few years ago, however not sure.  

[carbking]

In the for what its worth category:

 

LOTS of good guesses on this thread.

 

My comment about compression test, ignition test, fuel system test is basically "old school" WITH merit.

 

WHY?

 

If the compression is bad, NOTHING done to either the ignition or the fuel system will accomplish more than lightening one's wallet.

 

If the compression is good, but the ignition is bad, NOTHING done to the fuel system will accomplish more than lightening one's wallet.

 

So testing is done in a manner of not wasting time or money.

 

All of us CAN guess, and throw money at parts which may or may not help.

 

Personally, I gave up guessing in high school when my science teacher graded true/false questions 2 times (right minus wrong)! Taught me a very valuable lesson.

 

EDIT: not an expert on compression readings, but I was taught 15 times the compression ratio was a good cranking RPM rule of thumb.

 

Jon

Edited July 13, 2022 by carbking (see edit history)

[57j2olds]

Comp ratio is 6.5:1

 

PSI would be around 97.

[TerryB]

MoTors manual says compression value is 120 psi at engine cranking speed.

Edited July 13, 2022 by TerryB (see edit history)

[Frank DuVal]

On 7/12/2022 at 4:21 PM, 57j2olds said:

Downgrading the electronics meaning going HEI vs. stock points?

HEI was not mentioned. Just pertronix.

 

When the problem did not change I would have put the points back in. Infant mortality of new parts adds to confusion at times while troubleshooting. 
 

On 7/12/2022 at 6:20 PM, Bloo said:

it is important to keep in mind that it's chief advantage is it's ability to remain stable over time, not "run better" despite what 50+ years of advertising copy says.

 

YES!  Pertronix can only FIX odd issues like dwell angle changes from work bushings. Otherwise the engine will perform the same as with points. 
 

 

[yellowjacket]

Anyone here also have a 49 flathead 6 cylinder Olds engine they can run compression test on and get numbers?  Never an absolute match/indicator, but may put the 70PSI he's getting in some perspective.

Also, if you rerun compression test, I was always taught to do it on a warm engine if possible.  Run it for 15 minutes, then pull plugs and do the test.

[57j2olds]

16 hours ago, yellowjacket said:

Anyone here also have a 49 flathead 6 cylinder Olds engine they can run compression test on and get numbers?  Never an absolute match/indicator, but may put the 70PSI he's getting in some perspective.

Also, if you rerun compression test, I was always taught to do it on a warm engine if possible.  Run it for 15 minutes, then pull plugs and do the test.

Thank you for your comments!

 

I'll try this over the weekend.

[57j2olds]

Worked on this beast tonight....

 

At idle ok....slowly opening throttle....back fire through carb....stall....

 

Just like driving....

[carbking]

• Wondering if the re-build carb (Carter WA-1) I bought online is bad?

I may have made a bad assumption.

 

I assumed that the Carter WA-1 you bought on line is the CORRECT WA-1 for the 1949 Olds engine. The Olds was one of the largest engines using a WA-1. Most WA-1's are too small to fuel the 1949 Olds.

 

1949 Olds 6 with A/T Carter 709s

1949 Olds 6 with S/T Carter 710s

 

Even if the wrong carb, I don't think this is all of the problem; but it would be nice to know if the carb you have is correct.

 

Jon

[Oldtech]

Just curious but are the spark plugs good and gapped correctly ( .040). Cracked electrodes can do strange things. 

[57j2olds]

13 hours ago, carbking said:

• Wondering if the re-build carb (Carter WA-1) I bought online is bad?

I may have made a bad assumption.

 

I assumed that the Carter WA-1 you bought on line is the CORRECT WA-1 for the 1949 Olds engine. The Olds was one of the largest engines using a WA-1. Most WA-1's are too small to fuel the 1949 Olds.

 

1949 Olds 6 with A/T Carter 709s

1949 Olds 6 with S/T Carter 710s

 

Even if the wrong carb, I don't think this is all of the problem; but it would be nice to know if the carb you have is correct.

 

Jon

Jon-

 

How do I tell what carb I have now?

 

I just Googled that yellow sticker. 9668 is the wrong carb...

 

 

Edited July 22, 2022 by 57j2olds (see edit history)

[57j2olds]

7 hours ago, Oldtech said:

Just curious but are the spark plugs good and gapped correctly ( .040). Cracked electrodes can do strange things. 

Hi-

 

Yes. Recently put new plugs in.

[roysboystoys]

Could it be 966S ?

Chevy truck